1. Field of the Invention
The present invention relates to an X-ray image photographing method and an X-ray image photographing apparatus which enables photographing of a fine structure while using an X-ray source having a finite size.
2. Description of the Related Art
Conventionally, in a field of X-ray transmission image photographing, resolution of a detector has been at most ten and several μm. Accordingly, in order to photograph an image having a high resolution, photographing has been performed by magnifying projection of a specimen by using an X-ray source having a focal point size as small as possible, about 10 μm or less. That is, magnification ratio has been adjusted by adjusting distance relationships by reducing the distance from the X-ray source to the specimen and setting the distance from the specimen to the detector sufficiently large.
On the other hand, a method for performing photographing using a phase contrast and photographing using an absorption contrast with a same apparatus has been investigated (JP 2001-238871 A, JP 2006-26425 A, WO 2007/007473A, Hiromu OHARA, Tomonori GIDO, Akira ISHISAKA, and Chika HONDA, “The Principle and Images of Phase-Contrast Mammography”, Vol. 23 (2006), No. 2, pp. 27-33). For example, JP 2001-238871 A discloses a photographing method of an image with an emphasized edge by utilizing a phase contrast, with the ratio of the distance from the specimen to the detector and the distance from the X-ray source to the specimen set to 0.5.
However, in the photographing method of an X-ray transmission image using the above-mentioned magnified projection, the magnification ratio is determined by the arrangement of the X-ray source, the specimen, and the detector. Accordingly, under high magnification ratio photographing conditions for photographing a fine structure with a high resolution, it is not easy to freely adjust the ratio of phase contrast and absorption contrast while keeping the magnification ratio. On the other hand, in a method using electron beam such as SEM or TEM, it is difficult to photograph the structure inside a thick specimen although it is possible to obtain an image having a high resolution with respect to a specimen surface or a thin specimen.